The role of the interstitial cell of the kidney in experimental forms of hypertension will be studied. The effects of medullary implantation in the two different models of clip hypertension will be studied; in the first of these one kidney will be removed and a clip will be applied to one renal artery with the opposite kidney being untouched. These two models differ in several respects and the effects of medullary implants will be studied as well as measurements of medullary plasma flow. Work will continue on the spontaneously hypertensive rat (SHR), in particular a study of the different response to medullary grafts in the SHR rat which develops hypertension naturally compared with the SHR rat which develops hypertension only when the ureter is occluded.